Long-necked stegosaur defies reputation

Unlike modern giraffe, Portuguese dino probably did not lift its head much

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This artist's illustration shows what the fossils of a recently discovered stegosaur suggest the dinosaur looked like in life. Contrary to the dino group's popular image, this species had one of the longest necks among dinosaurs.

The classic image of a stegosaur calls to mind a grazing beast with short legs and a short neck, but a newly discovered species from Portugal was found to have one of the longest necks ever recorded for a dinosaur, relative to overall body size, according to a new study.

Miragaia longicollum, meaning "long-necked wonderful goddess of the Earth," had more neck vertebrae than almost any other dinosaur, tying the record previously set by three Chinese sauropods, the study found.

Octavio Mateus, who led the research, told Discovery News that the new species and other stegosaurs were four-legged plant eaters "with a row of plates and spines along the body from the neck to the tail." One swift swing of the tail could jab the sharp spines into would-be attackers.

But this was no ordinary squat stegosaur.

"Contrary to other stegosaur dinosaurs, Miragaia longicollum had a long neck with 17 vertebrae, which is as much as long-necked sauropod dinosaurs," added Mateus, a paleontologist at the Universidade Nova da Lisboa in Portugal.

He and his team analyzed the fossils, excavated near Miragaia in the municipality of Lourinha at a Late Jurassic site dating to between 144 and 159 million years ago. The fossils include the only known cranial remains for any European stegosaur. A juvenile, likely of the same species, was also discovered at the site.

The findings are published in the latest issue of Proceedings of the Royal Society B.

Unlike another famous modern long-necked animal, the giraffe, this Portuguese dinosaur probably did not lift its head much.

Deadly dinos"The anatomy of the vertebrae suggests that the neck was at shoulder level, horizontally parallel to the ground," Mateus explained. "They could raise the neck and head, but that was not the body's neutral position."

The researchers know how the dinosaur evolved such a long neck. Over time, some of its backbones transformed to become neck vertebrae, "making a longer neck and the body trunk shorter." Why this happened, though, remains a mystery, although two scenarios are possible.

The first is that the long neck might have permitted it to browse for foliage at a height not frequented by other prehistoric animals. The second is that males and females might have found the trait appealing, so it evolved due to sexual selection.

Mateus and his team are leaning toward the latter, since having a long neck would have put the dinosaur at risk of predators, who would've had a better chance of fatally injuring — even decapitating — the dino.

Throughout the animal kingdom then and now, however, members of the opposite sex often favor attributes, such as intense colors, long tails, exaggerated antlers "and, possibly, long necks," noted Mateus, even though these traits could reduce an individual's chances for survival.

Louis Jacobs, director of the Shuler Museum of Paleontology at Southern Methodist University, told Discovery News that the new study "is quite interesting because it shows a body form, and by inference, an ecological diversity among stegosaurs that was not suspected before."

Richard Butler, a Natural History Museum of London paleontologist, suggested that the newly found species livens up the otherwise rather predictable stegosaur image.

Butler said, "This new discovery reveals a surprising ... diversity among stegosaurs, which have generally been considered conservative animals."